Towards ubiquitous multihop wireless networks: addressing capacity and security challenges
Elizabeth Belding, Kimaya Mittal · 2007
While single-hop wireless networks are commonly deployed today, multihop wireless networks are still in early stages of development. These networks have tremendous potential to be the technology of choice for providing ubiquitous Internet connectivity since they enable truly pervasive, untethered, mobile access; minimize the need for expensive wired infrastructure; and are relatively easy to deploy and maintain. However, multihop scenarios significantly exacerbate several wireless networking challenges that must be addressed before these networks can become practical and useful. In this dissertation, we focus on two challenges that are particularly aggravated in multihop scenarios, and that we believe are among the most significant hurdles obstructing the widespread use of these networks. The first challenge that we address is limited capacity. Our contributions at the MAC and network layers of the protocol stack increase capacity utilization through improved spatial reuse of the medium. At the MAC layer, we present a comprehensive solution that mitigates the exposed terminal problem in static network topologies, thereby improving spatial reuse. At the network layer, we leverage user mobility to increase the bandwidth available to each user, which results in spatial redistribution of traffic and improved capacity utilization. A simulation-based evaluation of our solutions is presented. To facilitate efficient utilization of capacity, we design perceptive communication mechanisms that enable carrier-sense neighbors to communicate, and thereby coordinate medium access in a more sophisticated manner. We evaluate the feasibility and efficiency of perceptive communication on wireless hardware, and examine its application to calculate intra-flow contention. The second challenge that we address is the vulnerability of multihop wireless networks to attacks on the routing infrastructure. We demonstrate that popular multihop wireless routing protocols are replete with security flaws. We describe and classify several attacks on these protocols. Our secure routing protocol, ARAN, which we evaluate through both implementation and simulation, is robust against all identified attacks. In summary, this dissertation addresses critical challenges related to the limited capacity and security of multihop wireless networks. Our work significantly advances the state-of-the-art in wireless networking, and brings us closer to realizing the vision of ubiquitous multihop wireless networks.